The invention relates to an integral in-line check valve and, more specifically, to a windshield/glass washer nozzle having an integral check valve. Check valves are included in windshield/glass washer fluid feed lines to eliminate "drool" due to dynamic vehicle loads and when the hood is lifted. They also provide instantaneous response, that is, there is no delay from the fluid from the pump activation to fluid spray. Moreover, they provide a crisp start-up/shut-off and thereby reduce the amount of fluid that land on the surfaces.
In the prior art shown in FIG. 1, check valves are constituted by a two-piece nozzle housing to allow assembly of the check valve either by welding or gluing the check valve assembly onto the nozzle assembly.
According to the present invention, a one-piece housing and feed tube insert with valve seat eliminates a potential leakage due to incomplete welds or seal failure. According to the invention, an integral check valve is comprised of a coil spring, a valve element, and an insert or sleeve having a valve seat formed thereon, which is retained in the nozzle feed tube, preferably by a press fit. Thus, when the flexible tube or hose from the pump is slid over the feed tube and its retention barb, there is no possibility of leakage at the joint since the joint between the insert or sleeve is encompassed by the flexible feed tube. The present invention eliminates several parts thereby reducing the system cost and increasing reliability. Moreover, the check valve performance can be matched to needs of a particular nozzle such as a fluidic nozzle and the compact design allows the check valve to be incorporated with no increase in nozzle size.
The check valve of the present invention has a threshold or cracking pressure such that below this pressure no fluid will flow through the nozzle. Moreover, the check valve of the present invention will prevent air from entering the system through the nozzle which thereby will prevent fluid from draining back into the reservoir. This permits a faster response time since the response time is not slowed-up due to the feed tubes draining back into the reservoir after the system has been actuated. The feed tubes in the present invention will remain "primed" and the response will be nearly instantaneous. Finally, the relatively high cracking pressure and sealing ball provide a "crisp start-up and shut-off. Drops that land on surfaces other than the glass have been significantly reduced when compared to a standard fluidic nozzle.
According to the invention, the windshield washer system has a nozzle mounted on the vehicle for issuing wash fluid to the windshield and a check valve for a fluid circuit from a supply of wash fluid to the nozzle. The nozzle has a feed tube integrally formed therewith and the feed tube has annular walls defining a washer fluid flow path and a diameter of at least D. An internally formed spring shoulder and a coil spring having an upstream end and a downstream end with the downstream end bearing on the spring shoulder and a valve element, preferably a stainless steel ball, bears on the upstream end of the spring. A tubular insert has an inner end and an external diameter at least equal to the diameter D and sufficient to form an elongated wash fluid seal with the annular walls defining the wash fluid flow path and a ball valve seat is formed on the inner end of the tubular insert. Thus, when the flexible tube from the wash fluid supply is telescoped or fitted over the nozzle feed tube, the joint formed between the insert and the interior annular walls of the feed tube is totally within the tube so that any leakage at this point is directly back into the wash fluid supply thereby eliminating the potential leakage encompassed in prior art systems.
The present invention provides an easily assembled unit and is readily adaptable to the many different nozzle designs. A preferred cracking pressure is approximately 3 psi and this provides sufficient drooling resistance as well as a good start-up/shut-off characteristic. The flow rate test at 9 psi indicates less than 5% flow reduction when compared to the standard nozzle (i.e. one without a check valve). Standard cold temperature test results were not affected by the presence of the integral check valve.